Epoxy or Polyester as I replace large sections of Deck Core

[UNCIVILIZED]

Anything but pure white will heat up to a lot more than 120 deg. on a clear Spring day. As will a white deck, under a moderately warm sun if there's little breeze. So I'm curious to understand how a "post cure" at 120 deg. helps? And is this info to be found anywhere in their publications?

[toddedger]

Guys who just respond to posts with only the word "Bull" are just bing an ass hole. Why bother posting if you don't have something constructive to add to the topic?

[toddedger]

Will think about it Uncivilized, if you do a repair with some fast hardener in a 60° shop and the put it in the summer sun, then thats going to be a lot bigger change than if it had been post cured to 120°. 120° is what was recommended to me by Gougeon. I'm in Michigan and it seems to work. You could go higher I suppose. You can call them up if you don't believe me. I'm getting kind of tired of trying to be helpful and have every Internet expert argue with me.

[coastalexplorer]

So if we are all done hear? Then I suggest that as I wrote before it all comes down to a believe system and the many differing opinions of boat builders. This is surely a subject that collectively we will never be able to do better than to agree to disagree on.

Of course my submission was only hear say evidence. So I didn't really submit an opinion. I do find my self leaning towards identifying who are in fact the true professional's on here.

And for the most part it seems that it is the enthusiastic amateurs that seem to want to make the most controversial argument with them. The point about preparation & application techniques of the materials used appears to be the most common factor agreed on.

So perhaps the most valuable point about these discussions Is that 'while truth is in a person's mind even though their peers may have the greatest difficulty agreeing with them.' Having the opportunity to share our selection of aspects of truth with others offers them an opportunity to at least understand our point of view.

[coastalexplorer]

So if or are We all done here? Then I suggest that as I wrote before it all comes down to a believe system and the many differing opinions of boat builders. This is surely a subject that collectively we will never be able to do better than to agree to disagree on.

Of course my submission was only hear say evidence. So I didn't really submit an opinion. I do find my self leaning towards identifying who are in fact the true professional's on here.

And for the most part it seems that it is the enthusiastic amateurs that seem to want to make the most controversial argument with them. The point about preparation & application techniques of the materials used appears to be the most common factor agreed on.

So perhaps the most valuable point about these discussions Is that 'while truth is in a person's mind even though their peers may have the greatest difficulty agreeing with them.' Having the opportunity to share our selection of aspects of truth with others offers them an opportunity to at least understand our point of view.

[smj]

Originally Posted by coastalexplorer

So if we are all done hear? Then I suggest that as I wrote before it all comes down to a believe system and the many differing opinions of boat builders. This is surely a subject that collectively we will never be able to do better than to agree to disagree on.



Of course my submission was only hear say evidence. So I didn't really submit an opinion. I do find my self leaning towards identifying who are in fact the true professional's on here.



And for the most part it seems that it is the enthusiastic amateurs that seem to want to make the most controversial argument with them. The point about preparation & application techniques of the materials used appears to be the most common factor agreed on.



So perhaps the most valuable point about these discussions Is that 'while truth is in a person's mind even though their peers may have the greatest difficulty agreeing with them.' Having the opportunity to share our selection of aspects of truth with others offers them an opportunity to at least understand our point of view.

If I were you I would try to get past who the "true professionals " are and actually do some research of your own. Plenty of facts to be found.

[s/v Jedi]

There seem to be some old fart poly pullers that can't let go of he resin they have been using all their lives. I don't even know if any boats are still built with polyester... haven't they all switched to vinylester by now?

[ramblinrod]

Originally Posted by s/v Jedi

There seem to be some old fart poly pullers that can't let go of he resin they have been using all their lives. I don't even know if any boats are still built with polyester... haven't they all switched to vinylester by now?

Which means that about 95% of the plastic boats on the water today are polyester FRP, else it woulda been 98%. What's your point again?

[Souzag818]

Originally Posted by minaret

I've been telling people on this forum this (replace like with like, bond strength more than sufficient, doesn't create hard spots by making repair laminate stiffer than original, etc etc) for years. It's wasted breath, the epoxy manufacturers have thoroughly brainwashed the entire market. Leave the real work methods to us pro's, you'll never convince the neophytes of the truth. Ever.

The first dinghy I owned was an El Toro sail boat, circa 1978. Ply glassed over with polyester resin and a couple layers of 10 oz cloth. I peeled that cloth off in big sheets with my hands. Zero to minimal adhesion. Fast forward to 1997. Built a rowing dinghy with ply glassed over with two layers of 10 oz cloth, BUT epoxy resin instead. Still have that dinghy, and have never had a de-lamination problem. Maybe, just maybe, you need to open your eyes to the fact that epoxy might just be a better product. BTW, I also have "dabbled" in the boat repair business for 35 years, and I've never had a problem, but then I guess I'm still a "neophyte" trying to figure out the "real work method"...

[neilpride]

Originally Posted by s/v Jedi

There seem to be some old fart poly pullers that can't let go of he resin they have been using all their lives. I don't even know if any boats are still built with polyester... haven't they all switched to vinylester by now?

Dont talk like a ignorant, because you're not,,visit any pro FRP workshop and you can see how they are still using barrels of poly in lots of aplications, repairs or parts. In my case i can use West or Poly, im not brain sticked to the cheapest resin at all, its amazing the level of ignorance of some posters , for the record many insurance companys dont sign any check if the boat is not repaired using the same OEM materials...

[Southcoasting]

I've read a countless number of threads out there having the same arguments...In summary, here is what I learned:

1. Epoxy has superior bonding. Great for certain uses but not necessary for all uses.

2. Vinylester is the new polyester. Cheaper than epoxy, l little more than polyester. Stronger than poly at bond strength.

3. Polyester is what all your old plastic classics were laid up with. With proper care, many boats have lasted and have not sunk because of its use.

Yes, there has been delamination issues with it when using a core. mainly on decks where boats tend to flex most because of the stress from chainplates/spreaders/etc. Our boats flex with use. I would assume that my boat, born in 72, would have issues with delamination on decks mainly because the re-inforcement of the bukheads, additional hull stringers, etc was not built as it should be compared to the more robust and quality built boats out there. On my cabintop, there was no delamination issues...Mainly water ingression problems.

Properly used, epoxy would maybe have prevented this, maybe not...I don't know for sure. But as mentioned, with the amount of flexing I expect my boat to have as it is now, I think something would have had to give...For me and my Tartan, hull reinforcement will definitely be a job for the near future including bulkhead tab re-inforcement, adding wood stringers length wise along the inner topsides, and adding a couple more deck beams on bow and stern.

Any material used without proper prepwork, technique, mixing, and maintenance will not last as long as one that was put together like some DIY jobs I've seen. The same goes for high quantity production boats like my Tartan.

As for myself, I am simply using vinylester resin for my deck re-core and using a vinylester bonding paste to bond my balsa to the existing laminate underneath. Knowing this initial bond will be a mechanical bond, I will make a batch of resin using milled fiber and 1/4" chopped strand to brush on to bottom of my balsa and on the deck laminate, I will spread this bonding paste. The bonding paste has special properties to help with adhesion...and the milled fiber and chopped strand will help with strength and adhesion as well.

I have been particular about a clean surface and proper mixing ratios of my resin. I am just starting with the first section on my cabin top around the mast/cowl vents.

I hope it lasts...It should at least another 50 years as long as it's maintained...That's the key.

My project is up on the T34 forum: Recore project on #177!


A little more in hull re-inforcement: FIBERGLASS BOATBUILDING: Internal Hull Structures

[jimbunyard]

Originally Posted by glhotka

Question on Fiberglass. I have a 51' Formosa and have some soft spots in the deck (There is a bit of give there if I bounce up and down standing on the deck. For the most part, it is at the widest part of the deck just forward of the coach-house and runs about 4 feet from coach house forward.

As I am replacing core in the deck, the question of Epoxy vs. Polyester is coming up due to the significant difference in price between the 2. So if I cut out the outer skin, expose and replace the core with new hardwood, can I put on Polyester Resin, matt/woven?
Or since this needs to attach to the ground raw fiberglass edges of the cut opening, does it need to be epoxy.

There seems to be confusing suggestions when searching the interweb for the recommendation. I think I may have 20% less adherence strength with polyester to existing fiberglass than using epoxy, but I am not sure if 20% should be enough to sway the decision toward epoxy.

Here is how I am doing the repairs if this would impact the answer. I have removed all the teak off the deck already and removed the screws. I have done a "tap test" and found the spots that sound delaminated (thud vs solid sound) and have used a circular saw set shallow to cut through the upper deck skin. I started with a section about 30" wide by about 5 feet long. I removed all the core and replaced it with mahogany hardwood boards (that is what was in there when I opened it up). I am using small 5" by 12" strips that I epoxied to the lower skin with thickened epoxy, then when cured, used a thickened epoxy in and around all those boards to form one solid core. I then ground down the existing edges of my outer skin cut (about 3" wide) so that each layer of fiberglass matt would be slightly larger than the last and overlap and integrate into the existing deck. I put one layer of glass down ( the cross strandFirscross-strand matt, then one layer of 24 oz woven roving. I need to add a few more layers to get the spot thickened back up to about 1/8" of glass, but I stopped and am pondering this question of resin type. This one opening has already used more than 1.5 gallons of resin and the hardener that goes with it.
Given the fact that in this spot I have already put a layer of epoxy resin and glass down, does that change the answer on the material to use? And what about the next section I will be removing and repairing?

Love to get some feedback from the crew of "been there done that" here.

Most (all?) people who have done this job, and/or do it for a living, would recommend polyester resin over a coosaboard (or similar material) core. This would give the longest life for the money, be the most efficient in terms of application, and is much more than adequate in terms of 'strength' (whatever that means).

The effectiveness of a brainwashing is directly proportional to the strength of the brainwashee's conviction...or one could contemplate the Dunning-Kruger effect whilst reading this (and other [nudge nudge, wink wink]) thread(s)...

[ramblinrod]

Originally Posted by Souzag818

The first dinghy I owned was an El Toro sail boat, circa 1978. Ply glassed over with polyester resin and a couple layers of 10 oz cloth. I peeled that cloth off in big sheets with my hands. Zero to minimal adhesion. Fast forward to 1997. Built a rowing dinghy with ply glassed over with two layers of 10 oz cloth, BUT epoxy resin instead. Still have that dinghy, and have never had a de-lamination problem. Maybe, just maybe, you need to open your eyes to the fact that epoxy might just be a better product. BTW, I also have "dabbled" in the boat repair business for 35 years, and I've never had a problem, but then I guess I'm still a "neophyte" trying to figure out the "real work method"...

So you encountered one instance of poor polyester adhesion despite there being millions of examples of excellent polyester adhesion on the water today.

And your conclusion is polyester doesn't adhere?

I recently cut deck core samples out of my boat. Dry, perfect adhesion, attempts to remove the laminate destroyed the balsa. Can't get better adhesion than that.

The boat is 42 years old.

No maintenance to the deck until her 40th birthday, when I sprayed fresh glecoat on her, because I could. Looks like new.

This is consistent with pretty much any decently built polyester FRP boat, that some fool hasn't allowed water to penetrate the core.

Have you seen a 40 year old cold moulded epoxy boat with zero UV maintenance? I have.

With my eyes wide open, every single one has been a disaster, rotting in a yard because it is not economically feasible to repair. Not 1%, not 10%; 100%.

So what does this tell an experienced FRP guy?

A) The elToro wasn't built properly, or someone allowed water intrusion into the core.

B) The UV protective finish on your dinghy hasn't failed yet. How often have you revarnished or painted?

[s/v Jedi]

Originally Posted by neilpride

Dont talk like a ignorant, because you're not,,visit any pro FRP workshop and you can see how they are still using barrels of poly in lots of aplications, repairs or parts. In my case i can use West or Poly, im not brain sticked to the cheapest resin at all, its amazing the level of ignorance of some posters , for the record many insurance companys dont sign any check if the boat is not repaired using the same OEM materials...

Maybe you can read my post before reacting... I don't say "FRP workshops don't use poly anymore" so don't act like I did please

[s/v Jedi]

Originally Posted by ramblinrod

Which means that about 95% of the plastic boats on the water today are polyester FRP, else it woulda been 98%. What's your point again?

My point is that the world has moved on from polyester to vinylester and it wouldn't do you any harm to move on to vinylester as well, even (or even more so) when used to repair polyester boats. All your arguments for polyester are true for vinylester as well, plus it is factual a superior resin